The machining of small holes in an alloy steel turbine blade is often currently being done using an EDM machining process, in which the electrolyte used is typically deionized water (DI water). While such process provides several advantages over other known alternatives, as is known, the process can be quite slow. For example, in a typical turbine blade, there are as many as 50-100 holes required for each blade, and the time required to drill them is quite long. However, it has been shown that when ultrasonic energy is added to an EDM machining process the speed of material removal is increased. Therefore, applying ultrasonic energy to the turbine blade reduces the EDM machining time.
However, the problem exists as to how to efficiently couple ultrasonic energy to the blade. One alternative is to clamp the blade to the face of a half wavelength resonant horn. However, this is a very difficult task to accomplish because the combination of the horn, blade and clamp must sustain the ultrasonic vibrations. Problematically, the forces from the ultrasonic vibration tend to shake the clamp and horn apart after only a few seconds of operation.
Another alternative to vibrate the blade is to place the blade in a cavity machined into the horn face and pour epoxy into the cavity in order to hold the blade in place after the epoxy is cured. However, this requires that the horn, blade and epoxy all have to be at a set resonant frequency, which is not easily accomplished. Also, after one is finished with the machining operation the epoxy must be removed, also not an easy task to accomplish.
A more effective method of coupling the blade to the horn is to first determine the resonant half wavelength of the blade and directly drive it with a matching horn of the same frequency. However, the problem still exists as to how to attach the blade to the horn. The present invention addresses this problem.